Many fibers are formed from naturally occurring polymers. Various processing operations can be required to convert these polymers into fibers. In some instances, the resulting fibers can be referred to as regenerated fibers.
An important class of regenerated fibers includes fibers formed from cellulose. Cellulose is a significant component of plant matter, such as, for example, leaves, wood, bark, and cotton. Conventionally, a solution spinning process is used to form fibers from cellulose. A wet solution spinning process is conventionally used to form rayon fibers and lyocell fibers, while a dry solution spinning process is conventionally used to form acetate fibers. Rayon fibers and lyocell fibers often include cellulose having the same or similar chemical structure as naturally occurring cellulose. However, cellulose included in these fibers often has a shorter molecular chain length relative to naturally occurring cellulose. For example, rayon fibers often include cellulose in which substituents have replaced not more than about 15 percent of hydrogens of hydroxyl groups in the cellulose. Examples of rayon fibers include viscose rayon fibers and cuprammonium rayon fibers. Acetate fibers often include a chemically modified form of cellulose in which various hydroxyl groups are replaced by acetyl groups.
Fibers formed from cellulose find numerous applications. For example, these fibers can be used to form knitted or woven fabrics, which can be incorporated in products such as apparel or footwear. Fabrics formed from these fibers are generally perceived as comfort fabrics due to their ability to take up moisture and their low retention of body heat. These properties make the fabrics desirable in warm weather by allowing a wearer to feel cooler. However, these same properties can make the fabrics undesirable in cold weather. In cold and damp weather, the fabrics can be particularly undesirable due to rapid removal of body heat when the fabrics are wet. As another example, fibers formed from cellulose can be used to form non-woven fabrics, which can be incorporated in products such as personal hygiene products or medical products. Non-woven fabrics formed from these fibers are generally perceived as desirable due to their ability to take up moisture. However, for similar reasons as discussed above, the non-woven fabrics generally fail to provide a desirable level of comfort, particularly under changing environmental conditions.
It is against this background that a need arose to develop the cellulosic fibers described herein.